The first objective of this research is to establish definitely whether or not local anesthetics interact with membrane proteins. Our preliminary results, as well as the existing literature, suggest they do. Provided the interaction exists, we will determine the nature of this membrane protein-local anesthetic interaction. The significance of protein net charge and the involvement of protein conformation change in local anesthetic action will be studied. The characteristics of local anesthetic binding to the biological membranes (such as orientation, location, and number) and its importance will also be examined. Our preliminary studies have established the feasibility of the project and suggest an experimental approach. Included in the preliminary work is the synthesis of a homologous series of spin-labeled local anesthetics, testing of their pharmacological activities, and demonstration of their binding to nerve and erythrocyte membranes. The significance of the net charge of phospholipid head groups in binding of spin-labeled local anesthetics was also studied in liposome model membranes. The idea of using spin-labeled local anesthetics to study its interaction with membranes was tested in the preliminary work and found to be feasible. Spin labels, in conjunction with fluorescent probes, were also tried with good results. Both of these methods appear to be uniquely suited to accomplish the research objectives. In addition to a better understanding of local anesthetic action, the research is also expected to contribute significantly to the knowledge of membrane excitation and the molecular biology of membranes. As a result of this research, general principles governing the molecular mechanism of many such membrane active compounds emerge. BIBLIOGRAPHIC REFERENCE: Koblin, D.D., Wang, H.H. (1976) The effect of chemical modifiers on the interaction of a spin-labeled local anesthetic with human erythrocyte membranes. Biochemical Pharmacology 25: 1405-1413.